HTML and CSS design and build websites

The examples in this book all
follow these strict rules of XML.
One of the key benefits of this
change was that XHTML works
seamlessly with other programs
that are written to create and
process XML documents.
It could also be used with other
data formats such as Scalable
Vector Graphics (SVG) — a
graphical language written in
XML, MathML (used to mark
up mathematical formulae), and
CML (used to mark up chemical
formulae).
In order to help web page
authors move to this new syntax,
two main flavors of XHTML 1.0
were created:
● ● Strict XHTML 1.0, where
authors had to follow the rules
to the letter
● ● Transitional XHTML 1.0,
where authors could still use
presentational elements (such
as and ).
The transitional version of
XHTML was created because
it allowed authors to continue
to follow older practices (with a
less strict syntax) and use some
of the elements and attributes
that were going to be removed
from future versions of HTML.
There was also a third version
of XHTML 1.0 called XHTML
1.0 Frameset, which allowed
web page authors to partition
a browser window into several
"frames," each of which would
hold a different HTML page.
These days, frames are very
rarely used and are being phased
out.
HTML5
Released 2000
In HTML5, web page authors do
not need to close all tags, and
new elements and attributes will
be introduced. At the time of
writing, the HTML5 specification
had not been completed, but
the major browser makers had
started to implement many of
the new features, and web page
authors were rapidly adopting
the new markup.
Despite the fact that HTML5
is not yet completed, you can
safely take advantage of the
new features of the language as
long as you endeavour to ensure
that users with older browsers
will be able to view your pages
(even though some of the extra
features will not be visible to
them).
EXTRA MARKUP
180